Firing pins, springs, buffer, extractor spring, plunger, NOT the extractor, Links, O Rings, Action springs, Trigger assy, and a host of other items. Barrels are the problem area. 1100 Classic Trap has more parts that are the same as the 11-87 like the extractor and the bolt housing.

A quick perousal of the parts details and lists at the Remington site will tell much of the story.